Since Sir John Charnley pioneered the design and implementation of the total hip arthroplasty in the mid-1960s, joint replacement surgeons and orthopedic product companies have been striving to improve on the original design, often in collaboration. These improvements have been focused on the following goals:
i) Improvement of patient function
ii) Ease of insertion, through improved instrument design and surgical approach
iii) Reproduction of beneficial results, both from the patient and surgeon standpoints
iv) Longevity of the product
v) Smaller incisions
vi) Faster recovery
vii) Shorter operating time
viii) Multi-modal pain control parameters
Over the last fifty years, significant strides have been made in all of these goals. Newer products with improved materials have increased component longevity. Minimally invasive techniques, with multi-modal pain control, standardization of physical therapy protocols, and improved instrument design have all improved patient function and shortened recovery time. Procedures being performed more frequently by surgeons better versed in joint replacement surgery have led to more beneficially reproducible results.
One of the primary goals of all joint replacement arthroplasty techniques and designs is to remove as little bone as possible to accomplish the above goals. Always in the back of every joint replacement surgeon's mind is the fact that if the patient lives long enough, of if they put undue stress across the joint, whether due to being too active, weight gain, or other factors, the prosthesis will fail. The smaller amount of bone removed at the time of the primary arthroplasty, the less invasive revision necessary.
Unicompartmental arthroplasty of the knee has been part of the joint replacement surgeon's armamentarium for over 35 years. Commonly, only one of the three compartments in the knee has damage and is symptomatic. The other two are normal. The unicompartmental arthroplasty allows for the removal of the damaged compartment but preserves the patient's normal and native undamaged compartments.
The standard design of the traditional unicompartmental knee arthroplasty (when replacing the medial or lateral compartments) is to replace the distal and posterior condyles of the femur and the articular surface of the tibial plateau of the involved compartment. The meniscus is removed.
Often there is damage to the distal femoral weight bearing surface, yet the posterior femoral condyle and the tibial plateau articular surfaces are unaffected.
The following prior art references relate to and/or discuss one or more of the above described issues, and are each herein fully incorporated by reference: U.S. Patent Application Publication Nos: 2007/0032876 A1 entitled Knee Joint Prosthesis, published on Feb. 8, 2007, and 2008/0132895 A1 entitled instruments and Method for Arthroscopic Arthroplasty of the Knee, published on Jun. 5, 2008, both by inventor Ron Clark of Valparasio, Ind.